Method for allocating backhaul link resources in relay communication system, and method and apparatus for transmitting and receiving data using same

ABSTRACT

A method and a base station are described for transmitting a downlink signal in a wireless communication system. A configuration of orthogonal frequency division multiplexing (OFDM) symbols for a first partition of a subframe are transmitted through higher layer signaling. A relay-physical downlink control channel (R-PDCCH) contained in at least the first partition of the subframe is transmitted. If the R-PDCCH contains a downlink assignment, the first partition of the subframe is configured to be not used for a transmission for a physical downlink shared channel (PDSCH) corresponding to the R-PDCCH.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 13/148,069 filed on Aug. 5, 2011, which is the national Phaseof PCT International Application No. PCT/KR2010/000795 filed on Feb. 9,2010, and which claims priority to U.S. Provisional Application Nos.61/151,147 filed on Feb. 9, 2009 and 61/182,078 filed on May 28, 2009.The entire contents of all of the above applications are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for transmittingand receiving data in a relay communication system, and moreparticularly, to a method and apparatus for transmitting and receivingdata capable of allocating resources by dividing backhaul link resourcesinto plural partitions.

2. Discussion of the Related Art

According to a recent trend, a communication system has an increasedservice frequency band, and cells having decreased radiuses for highspeed communications and increased telephone traffic. This may causemany problems when applying the existing centralized cellular radionetwork method as it is. More concretely, a configuration of a radiolink has a degraded flexibility due to a fixed location of a basestation. This may cause a difficulty in providing efficientcommunication services in a radio environment where trafficdistributions or requested telephone traffic are severely changed.

In order to solve these problems, has been proposed a Multi-Hop relaysystem. This multi-hop relay system has the following advantages.Firstly, a cell service area may be increased by covering partial shadowareas occurring inside a cell area, and a system capacity may beincreased. Furthermore, an initial situation requiring less service isimplemented by using a relay. This may reduce the initial installationcosts.

FIG. 1 is a view schematically illustrating a relay communicationsystem.

A base station 101 forms a channel link with terminals 105 and 107.Here, the base station 101 may directly form a channel with the terminal105 through a link 121, or may form a channel with the terminal 107through a relay 103. A downlink channel 123 formed from the base station101 to the relay 103 is called a backhaul link. The backhaul link 123includes Relay-Physical Downlink Shared Channel (R-PDSCH) through whichdata is transferred from the base station 101 to the relay 103, andRelay-Physical Downlink Control Channel (R-PDCCH) through which controlinformation is transferred.

In a sub-frame where the base station performs a downlink backhaul tothe relay, control information and backhaul data of the relay have to betransferred. This may cause a difficulty in transmitting and receivingthe control information and the backhaul data together with a downlinklink sub-frame between the base station and a terminal. Furthermore,there is a limitation in controlling resource allocation according to atraffic amount of downlink backhaul data.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a method forallocating backhaul link resources capable of enhancing frequencyselectivity and controlling resources according to a traffic amount bydynamically performing a scheduling for resource allocation by a basestation over a backhaul channel.

Another object of the present invention is to provide a method forallocating backhaul link resources capable of implementing co-existenceof a backhaul link sub-frame between a base station and a relay, with adownlink sub-frame between the base station and a terminal.

Still another object of the present invention is to provide a method forallocating backhaul link resources capable of preventing time delayoccurring when a relay decodes backhaul link data, and a method fortransmitting and receiving backhaul link data using the same.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided a method for transmitting data in a method fortransmitting and receiving data in a relay communication system, themethod comprising: allocating a certain number of initial orthogonalfrequency division multiplexing (OFDM) symbol transmission periods in asub-frame of a downlink channel to a control channel that transferscontrol information of a terminal, wherein data is transmitted from abase station to a relay or a terminal through the downlink channel;dividing resource blocks excluded from the control channel of thesub-frame into at least two partitions in a frequency domain;determining whether or not each divided partition is allocated to therelay or the terminal as resources; and allocating data to thedetermined partition in order to transmit the partition to the relay orthe terminal through the downlink channel, wherein the partitiondetermined for the allocation of resources to the relay is transmittedto the relay through time division multiplexing (TDM) or frequencydivision multiplexing of both control and data channels of the relay.

Preferably, the step of dividing resource blocks into partitions mayfurther include transmitting information to the relay via a higher layercontrol signal, the information including the total number of dividedpartitions, a size of each partition and a location of resourcesoccupied by each partition.

Preferably, the partition determined for the allocation of resources tothe relay may undergo time division multiplexing (TDM) or frequencydivision multiplexing of both control and data channels of the relay.And, a certain number of initial OFDM symbol transmission periods of thepartition determined for the allocation of resources to the relay may beallocated as the control channel over the entire frequency band of thepartition.

Preferably, the partition determined for the allocation of resources tothe relay may undergo time division multiplexing (TDM) or frequencydivision multiplexing of both control and data channels of the relay,and the partition determined for the allocation of resources to therelay may include data of at least two relays. And, a control channel ofeach relay may be allocated with resources so as to match a resourcelocation of a frequency domain to which data of the relay has beenallocated.

Preferably, the step of determining whether or not each dividedpartition is allocated to the relay or the terminal as resources mayinclude determining an object for resource allocation according to eachpartition such that a resource allocation area to the terminal and aresource allocation area to the relay are semi-persistent over theentire frequency domain. And, the partition determined for theallocation of resources to the relay may undergo time divisionmultiplexing (TDM) or frequency division multiplexing of both controland data channels of the relay.

Preferably, each partition determined for the allocation of resources tothe relay may be allocated with data of one relay. And, controlinformation of another partition may be transmitted through a controlchannel of one partition.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is also provided an apparatus for transmitting data, the apparatuscomprising: a controller configured to divide downlink resources into atleast two partitions, and to determine whether or not each of thedivided partitions is allocated to a relay or a terminal as resources;and a transmitter configured to transmit data to the relay or theterminal through a downlink channel by allocating the data to thedetermined partition, wherein the partition determined for theallocation of resources is transmitted to the relay through divisionmultiplexing (TDM) or frequency division multiplexing (FDM) of bothcontrol and data channels of the relay.

Preferably, the transmitter may transmit information to the relay via ahigher layer control signal, the information including the total numberof divided partitions, a size of each partition and a location ofresources occupied by each partition.

Preferably, the partition determined for the allocation of resources tothe relay may undergo time division multiplexing (TDM) or frequencydivision multiplexing of both control and data channels of the relay.And, a certain number of initial OFDM symbol transmission periods of thepartition determined for the allocation of resources to the relay may beallocated as the control channel over the entire frequency band of thepartition.

Preferably, the partition determined for the allocation of resources tothe relay may undergo time division multiplexing (TDM) or frequencydivision multiplexing of both control and data channels of the relay,and the partition determined for the allocation of resources to therelay may include data of at least two relays. And, a control channel ofeach relay may be allocated with resources so as to match a resourcelocation of a frequency domain to which data of the relay has beenallocated.

Preferably, the controller may determine an object for resourceallocation according to each partition such that a resource allocationarea to the terminal and a resource allocation area to the relay aresemi-persistent over the entire frequency domain. And, the partitiondetermined for the allocation of resources to the relay may undergo timedivision multiplexing (TDM) or frequency division multiplexing of bothcontrol and data channels of the relay.

Preferably, each partition determined for the allocation of resources tothe relay may be allocated with data of one relay. And, controlinformation of another partition may be transmitted through a controlchannel of one partition.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is still also provided an apparatus for receiving data, theapparatus comprising: a receiver configured to receive data transmittedfrom a base station through a backhaul link channel; and a decoderconfigured to blind-decode received data over a predetermined frequencydomain, wherein the backhaul link channel is divided into two or morepartitions in a frequency domain, the partitions undergo time divisionmultiplexing (TDM) of both control and data channels of the relay, whensucceeding in decoding the control signal at a specific location in afrequency domain, the decoder recognizes that a control signal has beenallocated for a certain number of initial OFDM symbol transmissionperiod including frequency resources occupied by a corresponding controlchannel or a corresponding control channel, and the decoder decodesscheduled data through the control signal.

The present invention may be effective as follows. Firstly, the basestation dynamically performs a scheduling for resource allocationthrough a backhaul channel. This may enhance frequency selectivity andallow resources to be controlled according to a traffic amount.

Furthermore, according to the method for allocating backhaul linkresources of the present invention, a backhaul link sub-frame betweenthe base station and the relay may be transmitted and received togetherwith a downlink sub-frame between the base station and the terminal.And, time delay occurring when decoding backhaul link data by the relaymay be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically illustrating a relay communicationsystem;

FIG. 2 is a view illustrating each sub-frame structure of base stationand a relay;

FIG. 3 is a view illustrating an operation to transmit and receive asignal by a relay when backhaul link data consists of MBSFN sub-frames;

FIG. 4 is a view illustrating a configuration to divide resources of abackhaul link channel into a plurality of partitions in a frequencydomain according to a first embodiment of the present invention;

FIG. 5 is a view illustrating an embodiment in which backhaul linkresources are allocated to a relay in a semi-persistent manner;

FIG. 6 is a view illustrating an embodiment in which backhaul linkresources are allocated through time division multiplexing (TDM) of bothcontrol and data channels;

FIGS. 7 and 8 are views illustrating an embodiment in which backhaullink resources are allocated through frequency division multiplexing(FDM) of both control and data channels;

FIG. 9 is a view illustrating an embodiment in which backhaul linkresources are allocated by being divided into a plurality of partitionssuch that data channels of a terminal and a relay coexist over abackhaul link channel;

FIG. 10 is a view illustrating another embodiment in which backhaul linkresources are allocated by being divided into a plurality of partitionssuch that data channels of a terminal and a relay coexist over abackhaul link channel;

FIG. 11 is a view illustrating an embodiment in which the entirefrequency resources are classified into a region for allocation to aterminal, and a region for allocation to a relay;

FIG. 12 is a view illustrating an embodiment to indicate a location of apartition allocated as a backhaul link through a bit map;

FIG. 13 is a view illustrating an embodiment in which a control channelof a relay is allocated to occupy only part of a frequency domain of apartition allocated as a backhaul channel;

FIG. 14 is a view illustrating an embodiment in which a control channelof a relay is allocated to occupy only part of a frequency domain of apartition allocated as a backhaul channel;

FIG. 15 is a view illustrating an embodiment in which a control channelis allocated for transmission of resources which exist in anotherpartition;

FIG. 16 is a view illustrating an embodiment in which backhaul data of aspecific relay is allocated with respect to one partition;

FIGS. 17 to 19 are views illustrating modified embodiments of anembodiment explained with reference to FIG. 16;

FIG. 20 is a flowchart sequentially illustrating a method for allocatingbackhaul channel resources and transmitting data by a base stationaccording to a first embodiment of the present invention;

FIG. 21 is a block diagram schematically illustrating a configuration ofa base station according to a first embodiment of the present invention;and

FIG. 22 is a block diagram schematically illustrating a configuration ofa relay according to a first embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will beexplained in more details with reference to the attached drawings.Wherever possible, the same reference numerals will be used through thedrawings to refer to the same or similar parts, and the samedescriptions thereof are omitted. However, it should also be understoodthat embodiments are not limited by any of the details of the foregoingdescription, but rather should be construed broadly within its spiritand scope and it is intended that the present invention covermodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

A communication system of the present invention is a system forproviding various communication services such as voice and packet data,and includes a base station, a relay and a terminal. The communicationsystem will be explained with taking a Long Term Evolution (LTE) systemor an LTE-Advanced system as a representative example.

The terminal of the present invention may be referred to as a SubscriberStation (SS), a User Equipment (UE), a Mobile Equipment (ME), a MobileStation (MS), etc., and includes a portable device having acommunication function such as a portable phone, a PDA, a smart phoneand a notebook, or an unportable device such as a PC and avehicle-mounted device.

The base station of the present invention indicates a fixed pointcommunicated with a terminal, which may be referred to as an eNB(evolved-NodeB), a BTS (Base Transceiver System), an AP (Access Point),etc. One base station may have one or more cells, and an interface fortransmission of a user traffic or a control traffic may be used betweenbase stations. A downlink indicates a communication channel from thebase station to the terminal, and an uplink indicates a communicationchannel from the terminal to the base station.

A multiple access technique applied to a wireless communications systemof the present invention may include CDMA (Code Division MultipleAccess), TDMA (Time Division Multiple Access), FDMA (Frequency DivisionMultiple Access), SC-FDMA (Single Carrier-FDMA), OFDMA (OrthogonalFrequency Division Multiple Access), or well-known other modulationtechniques.

A multiple access scheme for downlink transmission may be different froma multiple access scheme for uplink transmission. For instance, an OFDMAscheme may be used for downlink transmission, whereas an SC-FDMA schememay be used for uplink transmission.

Hereinafter, preferred embodiments of the present invention will beexplained in more details with reference to the attached drawings.Wherever possible, the same reference numerals will be used through thedrawings to refer to the same or similar parts, and the samedescriptions thereof are omitted.

In a relay communication system, a base station transmits a downlinksignal to a relay through a backhaul link.

FIG. 2 is a view illustrating each sub-frame structure of base stationand a relay.

As shown, the sub-frame includes a control channel 210 and a datachannel 220. The control channel 210 includes a PDCCH, etc., and thedata channel 220 includes a PDSCH, etc. Preferably, in an LTE system, aplurality of PDCCHs perform an interleaving therebetween over thecontrol channel so as to enhance reliability of a control channel byimproving a frequency diversity.

In a sub-frame where the relay performs a downlink backhaul, the relayhas to transmit, to the terminal, a PDCCH and a Common Reference Signal(CRS) through an access link for one (the first) to four OFDM symbolperiods. More concretely, the relay operates in a transmission mode (Tx)for one (the first) to four OFDM symbol periods in a backhaul sub-frame,and has a transition gap 10 for converting into a reception mode (Rx)from a transmission mode (Tx).

The base station can transmit signals such as R-PDCCH and R-PDSCH to therelay at a region of PDSCH 220, i.e., after a time point whentransmission through the PDCCH ended. Accordingly, when being completelyready to receive a signal from the base station with consideration of aPDCCH transmission symbol period and the transition gap 10 of the basestation, the relay receives, from the base station, a relay controlchannel such as R-PDCCH and a relay data channel such as R-PDSCH for areception mode period 221 thereof.

After completely receiving the control channel and the data channel formthe base station, the relay converts the current mode from the receptionmode (Rx) to the transmission mode (Tx) so as to transmit a controlchannel to the terminal through an access link in the next sub-frame.Here, the relay configures a guard time, a transition gap 20 for modeconversion.

Under this configuration, the relay cannot transmit or receive data atsymbols corresponding to the transition gaps 10 and 20. Accordingly, asignal which should be received by the relay has to be transmitted at asymbol corresponding to a transition-completed section, not a symbolcorresponding to a transition start section. Therefore, there occurs alimitation in the number of symbols of sub-frames which can be used assubstantial backhauls in a backhaul link sub-frame by the relay.

According to a backhaul design method, the sub-frame transmitted to abackhaul link may be divided into variable sections 10 and 20 where asignal cannot be received by the relay, and a fixed section 221 where asignal can be received by the relay. As shown, the variable sections 10and 20 may be symbols of guard times corresponding to a transmissionsection 711 of the relay, and the transition gap 10 for converting thecurrent mode to a reception mode from a transmission mode, or thetransition gap 20 for converting the current mode to a transmission modefrom a reception mode.

Both of the variable sections 10 and 20, or only one of them may beimplemented according to a backhaul design method. For instance, thevariable section 20 may be omitted according to a timing design of therelay.

FIG. 3 is a view illustrating an operation to transmit and receive asignal by the relay when backhaul link data consists of MBSFN (MulticastBroadcast Single Frequency Network) sub-frames.

For instance, in a 3GPP E-UTRA (Evolved Universal Terrestrial RadioAccess) system, sub-frames received by the relay through a backhaul linkmay consist of MBSFN sub-frames. In a transmission mode (Tx) of therelay, a downlink sub-frame 310 is generally transmitted. In a receptionmode (Rx) of the relay, a backhaul link sub-frame 301 transmitted fromthe base station is received.

The relay may transmit a control channel (PDCCH) to terminals connectedthereto for one or two initial OFDM symbol periods of the backhaulsub-frame 301. And, the relay may receive a downlink signal from thebase station for data symbol periods 305 after the transition gap 10.Then, the transition gap 20 may be configured for conversion of therelay from the reception mode (Rx) to the transmission mode (Tx).

The base station may allocate radio resources to the relay in asemi-persistent manner or in a dynamic manner through a backhaul linkchannel according to a specific relay.

Hereinafter, a method for allocating radio resources through a backhaullink channel by the base station will be explained in more details.

FIG. 4 is a view illustrating a configuration to divide resources of abackhaul link channel into a plurality of partitions in a frequencydomain according to a first embodiment of the present invention.

As shown, the base station divides radio resources after an OFDM symbolperiod 401 into two or more partitions in a frequency domain, the radioresources transmitted through a PDCCH for transmitting controlinformation of the terminal directly connected to the base stationthrough a link.

In FIG. 4, it is assumed that the total number of divided partitions isfour (410, 420, 430 and 440). The partitions may have a constant size ordifferent sizes from each other. The base station transmits informationto the relay via a higher layer control signal, the informationincluding the total number of divided partitions, a size of eachpartition and a location of resources occupied by each partition.

Then, the base station determines whether to allocate each partition tothe terminal directly connected thereto through a link, or to a backhaullink for the relay when performing a downlink scheduling of acorresponding sub-frame.

Like in the conventional art, data (PDSCH) transmitted to the terminalis transmitted to each partition allocated to the terminal. And,scheduling information is included in a PDCCH 401 transmitted to theterminal. Therefore, in a case that one partition is used fortransmission to the terminal, two or more data channels (PDSCH) mayexist in one partition.

To the partition allocated as a backhaul link for the relay, should betransmitted a data channel (R-PDSCH) transmitted to the relay and acontrol channel (R-PDCCH) through which scheduling information istransmitted.

Here, a backhaul link partition determined for the allocation ofresources to the relay may be transmitted to the relay through timedivision multiplexing (TDM) or frequency division multiplexing (FDM) ofboth control and data channels of the relay.

FIG. 5 is a view illustrating an embodiment in which backhaul linkresources are allocated to a specific relay in a semi-persistent manner.

In FIG. 5, a frequency domain in which the backhaul data is transmittedis constantly configured in one sub-frame so that backhaul datatransmitted to the relay from the base station coexists with datatransmitted to the terminal directly connected to the base station. Thatis, since the base station allocates resources to the relay in asemi-persistent manner, an additional control channel (R-PDCCH) is notrequired. And, the base station may transmit the backhaul data throughthe resources allocated to the specific relay in a semi-persistentmanner.

Referring to FIG. 5, the base station divides radio resources after theOFDM symbol period 401 into five partitions in a frequency domain, theOFDM symbol period 401 where the PDCCH for transmitting controlinformation of the terminal directly connected to the base stationthrough a link is transmitted. Then, the base station determines whetherto allocate each partition to the terminal directly connected theretothrough a link, or to a backhaul link for the relay when performing adownlink scheduling of a corresponding sub-frame.

Referring to FIG. 5, the base station allocates a first partition to afirst terminal, a second partition to a first relay, a third partitionto a second terminal, a fourth partition to a second relay, and a fifthpartition to a third terminal. Here, the second and fourth partitionswhere backhaul data is transmitted to the first and second relaysallocate resources to the respective relays in a semi-persistent manner.This may require no additional control channel (R-PDCCH), and the basestation may transmit backhaul data through the resources allocated tothe specific relay in a semi-persistent manner.

However, when resources are allocated to the relay in a semi-persistentmanner, a dynamic scheduling is difficult to have a restriction oncontrolling resource allocation according to a traffic amount.

FIG. 6 is a view illustrating an embodiment in which backhaul linkresources are allocated through time division multiplexing (TDM) of bothcontrol and data channels.

When dynamically allocating resources to the relay according to atraffic amount, required is scheduling information indicating locationsof resources allocated to the respective relays, a used modulation andcoding scheme (MCS), etc. This scheduling information is transmitted tothe relay through a control channel (Control Channel; CCH). For one ortwo initial OFDM symbol periods in a sub-frame where backhaul data isreceived, the relay cannot receive the PDCCH 401 transmitted from thebase station since its PDCCH is transmitted. Therefore, an additionalcontrol channel 601 for the relay has to exist after a transmission timepoint of the PDCCH.

In the embodiment of FIG. 6, the base station divides radio resourcesafter the OFDM symbol period 401 into two partitions in a frequencydomain, the OFDM symbol period 401 where the PDCCH for transmittingcontrol information of the terminal directly connected to the basestation through a link is transmitted. Then, the base station allocatesa first partition as backhaul data transmitted to a first relay, andallocates a second partition as backhaul data for transmission to asecond relay. And, the base station allocates the data as a controlchannel 601 of the first and second relays by using the entire frequencyband of predetermined OFDM symbol periods after the guard time 10.

The control channel and the backhaul data channel of the relay undergotime division multiplexing (TDM). Accordingly, the base stationtransmits the control channel 601 to the relay by using the entirefrequency band for a partial OFDM symbol transmission period aftertransmitting the PDCCH 401. And, backhaul data 610 and 630 istransmitted according to scheduling information included in the controlchannel 601 of the relay.

However, in the embodiment of FIG. 6, the control channel of the relayoccupies the entire frequency band. This may cause a problem that a datachannel of the terminal directly connected to the base station through alink can not be configured together.

FIGS. 7 and 8 are views illustrating an embodiment in which backhaullink resources are allocated through frequency division multiplexing(FDM) of both control and data channels.

As shown in FIGS. 7 and 8, the control channel of the relay may betransmitted through FDM together with backhaul data. More concretely,the base station transmits the control channel by using some offrequency resources, and transmits the backhaul data according toscheduling information included in the control channel.

In the embodiment of FIG. 7, the base station divides radio resourcesafter the OFDM symbol period 401 into six partitions in a frequencydomain, the OFDM symbol period 401 where the PDCCH for transmittingcontrol information of the terminal directly connected to the basestation through a link is transmitted. Then, the base station allocatesa first partition to one control channel 701 to which schedulinginformation of all the relays is transmitted, a second partition to adata channel 510 of a first terminal, a third partition to a datachannel 520 of a first relay, a fourth partition to a data channel 530of a second terminal, a fifth partition to a data channel 540 of asecond relay, and a sixth partition to a data channel 550 of a thirdterminal.

Alternatively, as shown in the embodiment of FIG. 8, the respectiverelays are allocated with independent control channels 801 and 802. Thismay allow each relay to easily find its scheduling information. In thiscase, a location and a size of the control channel of the relay may bedetermined in a semi-persistent manner, thereby being transmitted to therelay via a higher layer signal.

However, in the embodiments of FIGS. 7 and 8, decoding delay may occursince the relays can decode the backhaul data channels 520 and 540 afterdecoding the control channels 801 and 803 thereof.

Hereinafter, will be explained a method for allocating resources capableof performing resource allocation by dividing backhaul link resourcesinto a plurality of partitions, through time division multiplexing (TDM)of a control channel and a backhaul data channel of a relay, and capableof capable of implementing a data channel of a terminal directlyconnected to a base station.

As shown in FIG. 4, the base station divides resources of a backhaullink channel into at least two partitions in a frequency domain withrespect to the entire resource regions excluding a control channelregion 401 of a Macro UE. Then, the base station determines whether ornot each divided partition is allocated to the relay or the terminal asresources. And then, the base station allocates resources to a partitiondetermined for the allocations of the resources through time divisionmultiplexing (TDM) of both control and data channels of the relay.

Accordingly, to a partition allocated as a backhaul link channel of therelay, a control channel of the relay is firstly transmitted over theentire frequency band of the corresponding partition for a certainnumber of initial OFDM symbol periods. The control channel has a fieldindicating a result that radio resources of the corresponding partitionare allocated as backhaul data of each relay. Each relay decodes acontrol channel of each partition, and decodes backhaul data of asubsequent resource region according to scheduling information includedin the control channel. Therefore, the control information and thebackhaul data of the relay undergo time division multiplexing (TDM) inone partition, and one partition allocated to the relay may havebackhaul data to be transmitted to two or more relays. Furthermore, thebase station may transmit backhaul data to one relay through two or morepartitions different from each other.

FIG. 9 is a view illustrating an embodiment in which backhaul linkresources are allocated by being divided into a plurality of partitionssuch that data channels of the terminal and the relay coexist over abackhaul link channel.

As shown, the base station divides radio resources after the OFDM symbolperiod 401 into four partitions in a frequency domain, the OFDM symbolperiod 401 where the PDCCH for transmitting control information of amacro terminal (Macro UE) directly connected to the base station througha link is transmitted. Then, the base station allocates first and fourthpartitions as data channels 510 and 540 of a first macro terminal and asecond terminal, and allocates second and third partitions as backhaulchannels 520 and 530 of the relay.

To the second and third partitions, control channels 901 and 903 of therelay are allocated over the entire frequency bands for a certain numberof initial OFDM symbol periods. However, FIG. 9 merely illustrates oneexample of the present invention. That is, the control channels may bealso transmitted through all the OFDM symbol periods of thecorresponding partition. The control channels of the relays of therespective partitions may have an interleaving structure therebetween.As shown in FIG. 9, the control channel transmitted to one relay may berestricted to exist on only one partition for simplified decoding of therelay. As a result, the control channels transmitted in the samepartition may be interleaved with each other in a correspondingpartition, but the control channels transmitted in different partitionsmay not be interleaved with each other.

In a third partition, two backhaul data channels 531 and 532 may undergofrequency division multiplexing (FDM) to be allocated to second andthird relays, respectively. However, the two backhaul data channels 531and 532 may undergo time division multiplexing (TDM) to be allocated todifferent OFDM symbols.

The control channels 901 and 903 of the relays may include controlinformation (scheduling information) of the first relay, the secondrelay and/or the third relay. That is, the control channel 901 of thesecond partition may include scheduling information of the first relay,the second relay or the third relay. And, the control channel 903 of thethird partition may also include scheduling information of the firstrelay, the second relay and/or the third relay.

Upon success of decoding a control channel in a specific partition, eachrelay recognizes that the control signal has been allocated for acertain number of initial OFDM symbol transmission periods of thepartition including the control channel. And, the relay decodes backhauldata by recognizing that a partition of which control channel has notbeen decoded has no relay control signal.

FIG. 10 is a view illustrating another embodiment in which backhaul linkresources are allocated by being divided into a plurality of partitionssuch that data channels of the terminal and the relay coexist over abackhaul link channel.

According to another embodiment of FIG. 10, in a case where backhauldata toward two or more relays exist in one partition, a size of acontrol channel corresponding to each backhaul data is controlled. Thismay control a location and the amount of resources of backhaul dataallocated to the relay.

As shown, if the base station transmits backhaul data 531 and 532 to atleast two relays in one partition (third partition), the number and alocation of frequency domain resources (resource block) occupied by acontrol channel of each relay are set to be consistent with the numberand a location of backhaul data transmitted to the corresponding relay.More concretely, a first partition and a second partition are allocatedas a backhaul channel of the relay, in which the first partition isallocated as a backhaul channel of a first relay, and the secondpartition is allocated as a backhaul channel for transmission ofbackhaul data of a second relay and a third relay. Here, controlchannels 1003 and 1005 of the second relay and the third relay areallocated to be consistent with sizes of resources occupied by backhauldata of the second and third relays.

The relay decodes a control channel with a cyclic redundancy check (CRC)masked by using its ID. Upon success of decoding a control channel at aspecific location, the relay recognizes that frequency resourcesoccupied by the control channel are allocated as backhaul datatransmitted thereto. Then, the relay performs decoding of the backhauldata. The relay repeatedly performs the operations over a predetermineddomain, and decodes backhaul data transmitted thereto. Under thisscheme, the control channel of the relay requires no information onresource allocation. Furthermore, and a location and the amount ofresources of backhaul data to the corresponding relay may be controlled.As a result, backhaul data to a plurality of relays may be effectivelymultiplexed to one partition having a fixed size.

In order to enhance a decoding performance with respect to the controlchannel of each relay and to reduce complexity, the number of frequencydomain resources (or size of a resource block) occupied by the controlchannel of the relay may be restricted to one of some candidates. As anexample to restrict a size of the control channel of the relay, thenumber of frequency domain resources occupied by the control channel ofthe relay may be restricted to multiples of a constant value.

Without specific information transmitted from the base station, eachrelay cannot check which partition has been allocated for transmissionof its backhaul data, and where backhaul data transmitted theretoexists. And, each relay may check a location of resources allocatedthereto, etc. by decoding its control channel. Accordingly, the controlchannel of the relay may be designed to have a fixed format, location,resource amount and MCS level so that the relay can check schedulinginformation through decoding. Alternatively, the control channel may bedesigned to have restricted types so that the relay can easily performblind decoding.

In some cases, in order to reduce the number of times that the relayattempts blind decoding, the base station may restrict a candidate groupof partitions which can be allocated to the relay in a semi-persistentmanner. And, the base station may inform each relay of a candidate groupof partitions which can be allocated to the relay via a higher layersignal. In this case, the number of times that the relay attempts blinddecoding may be reduced since the relay performs blind decoding withrespect to only partitions which can be allocated as a backhaul link.

FIG. 11 is a view illustrating an embodiment in which the entirefrequency resources are classified into a region for allocation to theterminal, and a region for allocation to the relay.

As shown, backhaul link frequency resources are semi-persistentlyclassified into a region of ‘A’ where backhaul link frequency resourcesare allocated to the terminal, and a region of ‘B’ where backhaul linkfrequency resources are allocated as a backhaul link of the relay. Inthe region of ‘B’, a control channel 1101 of the relay is allocated overthe entire frequency band, and backhaul data of the relay may beallocated to each relay according to each partition 530, 540 and 550.Therefore, the relay has only to perform blind decoding of the controlchannel 1101 with respect to the region of ‘B’ allocated thereto, notover the entire frequency band. This may shorten decoding time.

According to another embodiment of the present invention, the basestation may semi-persistently restrict a candidate group of partitionswhich can be allocated to each relay, and may inform each relay via ahigher layer signal. In this case, each relay has only to perform blinddecoding with respect to only partitions which can be allocated thereto.This may reduce the number of times that each relay performs blinddecoding.

FIG. 12 is a view illustrating an embodiment to indicate a location of apartition allocated as a backhaul link through a bit map.

As shown, the base station may transmit a bitmap 1201 to each relay byusing predetermined some OFDM symbols, the bitmap indicating whethereach partition has been allocated as a backhaul link.

The relays may check a type of partitions allocated as a backhaul linkby decoding the bitmap 1201, and may perform blind decoding with respectto only a control channel of partitions allocated as a backhaul linkbetween control channels 1203 and 1205.

As shown, the bitmap 1201 is included in some OFDM symbols of the secondpartition. This may allow each of the first relay, the second relay andthe third relay to check a control channel including its controlinformation through the bitmap.

According to another embodiment of the present invention, the bitmap maybe transmitted by utilizing resources of two or more differentpartitions, and the partition where the bitmap exists may be set(established) to be always allocated as a backhaul link channel.

According to another embodiment of the present invention, the controlchannel transmitted to the relay may exist only in some of the entirefrequency domain of one partition allocated to the relay.

FIG. 13 is a view illustrating an embodiment in which a control channelof a relay is allocated to occupy only part of a frequency domain of apartition allocated as a backhaul channel.

As shown, a second partition and a third partition are allocated tofirst to third relays as backhaul link channels.

To the second partition, backhaul data of the first relay is allocated.A location of a control channel 1301 of the second partition correspondsto one or more initial OFDM symbols of the second partition. Here, thecontrol channel 1301 of the second partition may not be allocated overthe entire frequency domain of the second partition, but may beallocated over part of the entire frequency domain. In this case, afrequency domain having not been allocated as the control channel 1301may be used to transmit backhaul data.

The third partition is allocated as backhaul data of the second andthird relays is allocated. Like in the second partition, a controlchannel 1303 of the third partition may not be allocated over the entirefrequency domain of the third partition, but may be allocated over someof the entire frequency domain. In this case, a frequency domain havingnot been allocated as the control channel 1303 may be used to transmitbackhaul data.

The control channels 1301 and 1303 may include control information(scheduling information) of the first relay, the second relay or thethird relay. That is, the control channel 1301 of the second partitionmay include scheduling information of the first relay, the second relayand/or the third relay. And, the control channel 1303 of the thirdpartition may also include scheduling information of the first relay,the second relay and/or the third relay.

FIG. 14 is a view illustrating an embodiment in which a control channelof a relay is allocated to occupy only part of a frequency domain of apartition allocated as a backhaul channel.

As shown, a second partition and a third partition are allocated tofirst to third relays as backhaul link channels.

Here, the number and a location of frequency domain resources (resourceblock) occupied by a control channel of each relay are set to beconsistent with the number and a location of backhaul data transmittedto the corresponding relay. More concretely, a first partition and asecond partition are allocated as a backhaul channel of the relay, inwhich the first partition is allocated as a backhaul channel of a firstrelay, and the second partition is allocated as a backhaul channel fortransmission of backhaul data of a second relay and a third relay. Here,control channels 1403 and 1405 of the second relay and the third relayare allocated to be consistent with sizes of resources occupied bybackhaul data of the second and third relays, respectively.

As shown, to the second partition, backhaul data of the first relay isallocated. A location of a control channel 1401 of the second partitioncorresponds to one or more initial OFDM symbols of the second partition.Here, the control channel 1401 of the second partition may not beallocated over the entire frequency domain of the second partition, butmay be allocated over part of the entire frequency domain. In this case,the control channel 1401 may include scheduling information of the firstrelay, and a frequency domains having not been allocated as the controlchannel 1401 may be used to transmit backhaul data of the first relay.

To the third partition, backhaul data of the second and third relays isallocated. The control channels 1403 and 1405 of the third partition areallocated to be consistent with sizes of resources occupied by backhauldata of the second and third relays, respectively.

FIG. 15 is a view illustrating an embodiment in which a control channelis allocated for delivery of scheduling information on resources whichexist in another partition.

In this embodiment, frequency resources of another partition arescheduled through a control channel in one partition. More concretely, afirst relay receives backhaul data 520 by being allocated with somefrequency resources of second and third partitions, and schedulinginformation thereof is transmitted through a control channel 1501 of thefirst relay which exists in the second partition. In the thirdpartition, the control channel of the first relay does not exist.

Therefore, it is possible to schedule some of frequency resources ofanother partition through a control channel of one partition.

For simple implementations of resource allocation of the relay and adata receiving operation, scheduling is performed so that backhaul datafor one relay is allocated to one partition according to anotherembodiment of the present invention.

FIG. 16 is a view illustrating an embodiment in which backhaul data of aspecific relay is allocated with respect to one partition.

As shown, a backhaul channel of a specific relay is allocated as aspecific partition used for transmission of backhaul data. Accordingly,scheduling is performed so that backhaul data of one relay can beallocated to a specific partition. In this case, resource waste mayoccur due to the limitation that data of one relay is allocated to onepartition. Therefore, it is preferable to properly control a size ofresources occupied y each partition. For instance, in a 3GPP LTE system,a size of the partition may be controlled as a unit of three resourceblocks. In a case where one relay is allocated with a plurality offrequency resources, overhead of a control channel may be increased inproportional to a size of allocated resources. In order to prevent thisproblem, resources of another partition may be scheduled through acontrol channel of one partition.

As shown in FIG. 16, in this embodiment, the entire frequency resourcesare divided into eight partitions having a fixed size, i.e., a smallersize of frequency resources than that of the aforementioned embodiment.And, each partition may be allocated as a data channel of a terminal(macro UE) or a backhaul link channel of a relay. Frequency domainresources of a data channel allocated to one terminal may be allocatedto a frequency resource domain larger than one partition.

As shown, a data channel 510 of a first terminal is allocated as somefrequency resources of first and second partitions, a data channel 520of a second terminal is allocated as the rest resources of the secondpartition, and a data channel 540 of a third terminal is allocated asresources of seventh and eighth partitions.

The rest partitions are allocated as a backhaul channel of the relay,and a first relay may be allocated with resources by allocating third tofifth partitions as its backhaul data channel, through a control channel1601 which exists in a third partition. In some cases, a control channel1603 and a backhaul data (540) channel may be allocated with resourcesthrough one partition such as a second relay.

This embodiment is similar to the aforementioned embodiment explainedwith reference to FIG. 15 in the aspect of results of resourceallocation, but is different in that control channels 1601 and 1603 ofthe relays always occupy the entire frequency domain of one partition.This may result in an advantage to lower complexity when implementingthe relays in that a location of resources is fixed, the resources to besearched so as to blind-decode control information included in a controlchannel by each relay.

FIGS. 17 to 19 are views illustrating modified embodiments of theembodiment explained with reference to FIG. 16.

In FIGS. 17 to 19, it is assumed that a partition unit of a backhaullink channel, or an allocation unit of a data channel is 3RB. However,this is merely exemplary. If a control channel element (CCE) suitablefor a relay control channel (R-PDCCH) is determined, the CCE or aninteger multiple of the CCE are preferably used.

Preferably, the R-PDCCH allocated to one relay is transmitted with afixed size rather than a variable size. In some cases, the R-PDCCH maybe transmitted over plural OFDM symbols.

The base station may configure, via a higher layer signal, the number ofOFDM symbols occupied by the R-PDCCH with respect to each relay. ThisR-PDCCH has a capability to schedule a data channel (R-PDSCH) allocatedto a corresponding relay. In FIG. 17, a data channel (R-PDSCH) toward acorresponding relay which exists in another partition is scheduledthrough an R-PDCCH which exists in one partition.

In FIG. 18, a first R-PDCCH is designed to indicate a followingadditional R-PDCCH. For instance, in an assumption that a first OFDMsymbol of the R-PDCCH is downlink scheduling information, whether uplinkscheduling information exists in a subsequent OFDM symbol may beindicated through an indicator bit included in the first symbol. Here,the two symbols (downlink scheduling information and uplink schedulinginformation) may not be necessarily located in a consecutive manner. Forconvenient design of the R-PDCCH, the number of R-PDCCH symbols (Nsymbols, N=1, 2, 3, . . . , N_max) of all the relays may be fixed.

As shown in FIG. 19, it is possible to transmit the R-PDCCH by designingin all partition units or allocation units. This scheme may be appliedto a case where a channel coding, an MCS establishment, etc. areindependently performed since the R-PDSCH which exists in each partitioncorresponds to a different transport block. As a combination of theschemes shown in FIGS. 17 and 18, when one relay receives the R-PDSCHthrough N partitions, the R-PDCCH which performs a scheduling may be setto exist in partitions having the number of ‘M’ equal to or smaller thanthe ‘N’ (M=1, 2, 3, . . . , N). Here, the ‘M’ may be set to be thenumber of transport blocks to be transmitted to a corresponding relay,or the number of codewords.

FIG. 20 is a flowchart sequentially illustrating a method for allocatingbackhaul channel resources and transmitting data by a base stationaccording to a first embodiment of the present invention.

As shown, the base station divides radio resources after an OFDM symbolperiod 401 into two or more partitions in a frequency domain, the radioresources transmitted through a PDCCH for transmitting controlinformation of the terminal directly connected to the base stationthrough a link (S2001).

The base station transmits information to the relay via a higher layercontrol signal, the information including the total number of dividedpartitions, a size of each partition and a location of resourcesoccupied by each partition (S2003).

Then, the base station determines whether to allocate each partition tothe terminal directly connected thereto through a link, or to a backhaullink for the relay when performing a downlink scheduling of acorresponding sub-frame (S2005).

To a partition allocated for the terminal, data (PDSCH) transmitted tothe terminal is transmitted like in the conventional art. And,scheduling information is included in the PDCCH 401 transmitted to theterminal. Therefore, when one partition is used for transmission to theterminal, two or more data channels (PDSCH) may exist in one partition.

To a partition allocated as a backhaul link to the relay, have to betransmitted a data channel (R-PDSCH) transmitted to the relay, and acontrol channel (R-PDCCH) to which scheduling information istransmitted. Here, the backhaul link partition determined for allocationresources to the relay may be transmitted to the relay through timedivision multiplexing (TDM) or frequency division multiplexing (FDM) ofboth control and data channels of the relay.

Then, data is allocated to the corresponding resources with respect to apartition allocated as a channel for data transmission to the terminal,and a partition allocated as a channel for transmission of controlinformation and data to the relay (S2007).

Then, a data-allocated packet is transmitted through a backhaul linkchannel (S2015).

FIG. 21 is a block diagram schematically illustrating a configuration ofa base station according to a first embodiment of the present invention.

The base station comprises a transmitter 2101, a controller 2103 and areceiver 2105.

The controller 2103 divides downlink resources into two or morepartitions in a frequency domain, and determines whether to allocateresources to the relay or the terminal with respect to each of thedivided partitions.

The transmitter 2101 allocates data to the determined partition, andtransmits the data to the relay or the terminal through the downlinkchannel.

The partition determined for allocation of resources to the relay istransmitted to the relay through time division multiplexing (TDM) orfrequency division multiplexing (FDM) of both control and data channelsof the relay. Here, the resource allocation through the control and datachannels of the relay may be implemented through the aforementionedvarious embodiments.

FIG. 22 is a block diagram schematically illustrating a configuration ofa relay according to a first embodiment of the present invention.

The relay comprises a transmitter 2201, a decoder 2203 and a receiver2205.

The receiver 2205 receives data transmitted from a base station througha backhaul link channel.

The decoder 2203 blind-decodes receives data in a predeterminedfrequency domain, thus to search scheduling information on its backhauldata. If the decoder 2203 succeeds in decoding a control channel at aspecific location in a frequency domain, the decoder 2203 recognizesthat data has been allocated to frequency resources occupied by thecontrol channel, and then decodes backhaul data.

In addition, the above various embodiments may be implemented by using,computer software, hardware, or some combination thereof. For instance,the method of the present invention may be stored in a storage medium(e.g., internal memory, flash memory, hard disc, etc.), or may beimplemented in codes or commands inside a software program that can beexecuted by a processor such as a microprocessor inside a UE.

It will also be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover modifications and variationsof this invention provided they come within the scope of the appendedclaims and their equivalents.

What is claimed is:
 1. A method for transmitting a downlink signal by abase station in a wireless communication system, the method comprising:transmitting a configuration of orthogonal frequency divisionmultiplexing (OFDM) symbols for a first partition of a subframe throughhigher layer signaling; and transmitting a relay-physical downlinkcontrol channel (R-PDCCH) contained in at least the first partition ofthe subframe, wherein if the R-PDCCH contains a downlink assignment, thefirst partition of the subframe is configured to be not used for atransmission for a physical downlink shared channel (PDSCH)corresponding to the R-PDCCH.
 2. The method of claim 1, wherein thedownlink assignment indicates whether or not the PDSCH exists in asecond partition of the subframe.
 3. The method of claim 2, wherein thefirst partition is located before the second partition in a time domainof the subframe.
 4. A base station (BS) for transmitting a downlinksignal in a wireless communication system, the base station comprising:a radio frequency (RF) unit; and a processor, wherein the processor isconfigured to: transmit configuration of orthogonal frequency divisionmultiplexing (OFDM) symbols for a first partition of a subframe throughhigher layer signaling; and transmit a relay-physical downlink controlchannel (R-PDCCH) contained in at least the first partition of thesubframe, wherein if the R-PDCCH contains a downlink assignment, thefirst partition of the subframe is configured to be not used for atransmission for a physical downlink shared channel (PDSCH)corresponding to the R-PDCCH.
 5. The base station of claim 4, whereinthe downlink assignment indicates whether or not the PDSCH exists in asecond partition of the subframe.
 6. The base station of claim 5,wherein the first partition is located before the second partition in atime domain of the subframe.